In a legacy wireless communication system, a user equipment measures/estimates a downlink channel using a cell-specific reference signal (hereinafter abbreviated CRS) from a base station to generate/calculate channel state information and may demodulate data based on the channel measured/estimated using the CRS.
Meanwhile, in an enhanced wireless communication system, a channel state information-reference signal (hereinafter abbreviated CSI-RS), which is a separate reference signal for the CSI, and a demodulation reference signal (hereinafter abbreviated DMRS), which is a separate reference signal for demodulation, are introduced. A user equipment in a transmission mode using the CSI-RS and the DMRS generates/calculates the CSI based on the channel measured/estimated using the CSI-RS and may perform demodulation based on the channel measured/estimated using the DMRS.